Ultraviolet light system for use in heating, ventilation, and air-conditioning systems

ABSTRACT

An ultraviolet light-emitting device can be used to inactivate pathogens in air circulating through an HVAC system. The UV device can include a first and optionally a second UV light source that emits UV light at a predetermined peak wavelength that is selected to inactivate a specific pathogen. The second UV light source can emit a different predetermined peak wavelength that is selected to inactivate a different pathogen. The UV light sources can be included in a housing located within the HVAC system. Two or more housings can be placed within the same or different components of the HVAC system. The two or more housings can include UV light sources that emit the same or different peak wavelengths. An amplifier can be used to increase the intensity of the UV light emitted such that a desired percentage of a specific pathogen is inactivated.

TECHNICAL FIELD

Ultraviolet (UV) light can be used to kill viruses or bacteria. A UVlight system can be used in an air system of a residential building,commercial building, automobile, or airplane.

BRIEF DESCRIPTION OF THE FIGURES

The features and advantages of the embodiments will be more readilyappreciated when considered in conjunction with the accompanyingfigures. The figures are not to be construed as limiting any of theembodiments.

FIG. 1 is a schematic illustration of an HVAC system with a UVlight-emitting device according to certain embodiments.

FIG. 2 is a cross-sectional view of a UV light-emitting device accordingto certain embodiments.

FIG. 3 is a cross-sectional view of a UV light-emitting device accordingto certain other embodiments.

DETAILED DESCRIPTION

Ultraviolet (“UV”) light, which is a form of electromagnetic radiation,can be used to inactivate microbial contaminants and viruses(collectively referred to as “pathogens”) in a variety of applicationsand industries. UV lights used for this purpose are commonly referred toas germicidal UV lights (“GUV” lights). For example, UV light can beused in water treatment facilities, food processing facilities, swimmingpools, hot tubs, surfaces, and ducts for heating, ventilation, and airconditioning (“HVAC”) systems. A variety of lamps can be used to emit UVlight including, but not limited to, low-pressure, mercury-vapor lampsand light-emitting diode (“LED”) lamps.

The wavelength from UV light is in the range of 10 to 400 nanometers(nm) and has a shorter wavelength than visible light, but a longerwavelength than X-ray radiation. UV light emitted at certain wavelengthscan inactivate a pathogen by damaging the pathogen's DNA/RNA so that itcannot reproduce; therefore, rendering it harmless, even though thepathogen may not be killed. Pathogens vary in their sensitivity tospecific UV wavelengths. For example, ultraviolet-A (UV-A) light at a365 nm wavelength has been shown to have antimicrobial activity againstpathogens such as Escherichia coli and Candida albicans. By way ofanother example, some studies have shown that SARS-CoV-2, commonlyreferred to as COVID-19, has a susceptibility to ultraviolet-C (UV-C)wavelengths in the range of 267-297 nm for surface treatment and 222 nmfor air treatment.

UV-A, UV-B, and UV-C are all forms of UV light, with UV-C having theshortest wavelength (100-280 nm), UV-B having the second shortestwavelength (280-315 nm), and UV-A having the longest wavelength (315-400nm) of the three forms. UV-C, having the shortest wavelength, has beenshown to be the most effective against certain pathogens and can bethought of as being stronger than UV-A. UV-C from sunlight is absorbedby the Earth's ozone layer and does not penetrate through theatmosphere. Accordingly, all UV-C light is artificially produced via UVlamps.

Energy density (commonly referred to as the UV dose) and irradiance(commonly referred to as the UV intensity) are two key parameters thatcan help characterize the performance of a UV light source. Irradiancecan be defined as the instantaneous number of photons at a specificwavelength or range of wavelengths striking a surface per unit area andis generally expressed in units of watts per square centimeter (W/cm²).Energy density is the time-integral of irradiance and represents thetotal sum of photons of a specific wavelength or wavelength rangereceived by a specific area of the surface within a specific length oftime and is generally expressed in units of joules per square meter(J/m²). Accordingly, both the UV dose and the intensity play a crucialrole for sanitizing surfaces or air.

D90 values indicate the necessary radiant exposure of an ultravioletdose to inactivate 90% of a particular pathogen. Below is a partialreproduction of a table reporting D90 values from various studiesperformed on Coronaviruses under UV light exposure.

Microbe D90 Dose (J/m²) Coronavirus  6.6 SARS-CoV-2 (Italy-INMI1) 12.3SARS Coronavirus (Frankfurt 1) 16.4 SARS-CoV-2(SARS-CoV-2/Hu/DP/Kng/19-027) 41.7

To inactivate a sufficient percentage of a pathogen for sanitationand/or sterilization purposes, not only must the correct wavelength beemitted, but also the UV dose must meet or exceed the minimum requireddose. The UV dose can be increased by adjusting the intensity of the UVlight output, the exposure time of the pathogen to the UV light, or acombination of both.

Current UV light systems for HVAC systems have several disadvantages.One significant disadvantage is the inability to attain the requisite UVdose to protect people against exposure to a pathogen from recirculatedair through the HVAC system. Another disadvantage is that the UV lampmay emit a wavelength that inactivates one pathogen but does notinactivate other pathogens. This inability to emit a range ofwavelengths or different wavelengths can result in protection existingfor fewer pathogens than is needed. Thus, there is a criticalneed—especially for inactivating a plurality of different bacteria andviruses—for improved UV systems that can be used in HVAC systems.

It has been discovered that an ultraviolet light-emitting device for usein a heating, ventilation, and air conditioning system can be used toinactivate a variety of bacteria and viruses. The novel device caninclude one or more UV light sources that emit UV-A, UV-B, UV-C, orcombinations thereof in a variety of wavelengths or wavelength ranges.The novel device can also include features and/or components thatincrease the UV dose via amplification of the light intensity orexposure time. By increasing the UV dose, a greater number or percentageof pathogens can be inactivated compared to traditional UV systems.

According to any of the embodiments, an ultraviolet light-emittingdevice for use in a heating, ventilation, and air conditioning system,the device can include: a first housing located within a component ofthe heating, ventilation, and air conditioning system, wherein at leasta portion of the housing is transparent; a first ultraviolet lightsource located within the housing and adjacent to the portion of thetransparent housing, wherein the ultraviolet light source emitsultraviolet light at a pre-selected peak wavelength; and a power sourcefor supplying power to the first ultraviolet light source.

Turning to the figures, FIG. 1 is a schematic illustration of a heating,ventilation, and air conditioning (“HVAC”) system 100. As used herein,the phrase “HVAC system” means any system that is designed to heat andcool an interior space. As can be seen in FIG. 1, the HVAC system 100can include any or all of the following components that are common forheating and cooling a building: one or more return air ducts 121; areturn plenum 122; a furnace 123; an evaporator coil 124; a supplyplenum 125; a transformer/power supply 126; and one or more supply airducts 127. The HVAC system 100 can include other components not shown inthe drawings depending on the interior space the HVAC system is designedto heat and cool. By way of example, the components of an HVAC systemfor use in a vehicle can include an A/C compressor, a condenser, aradiator fan, a blower fan, an evaporator, tubing, and a refrigerantamong other components. It is to be understood that the UVlight-emitting device can be used in any system designed to heat andcool an interior space including, but not limited to, a house, officebuilding, workshop, motor vehicle, temporary shelter, warehouse, andmanufacturing facility.

The HVAC system 100 includes a UV light-emitting device 110. As shown inFIG. 2, the UV light-emitting device 110 can include a housing 111. Thehousing 111 can be a variety of shapes and sizes. For example, as shownin FIG. 2, the housing 111 can have a conical shape. As shown in FIG. 3,the housing 111 can have a cylindrical shape. The housing 111 can alsobe cubic, rectangular, or other shapes. A portion of the housing 111,for example as shown in FIG. 2, can be opaque. An opaque portion of thehousing can be made from a variety of materials. Non-limiting examplesof opaque materials include metals, metal alloys, and hardened plastics.

The dimensions of the housing 111 can be selected based on a variety offactors. Such factors can include, without limitation, the ability tohouse the dimensions and desired number of the UV light source(s) 112contained within the housing, the dimensions of the component of theHVAC system 100 in which the housing is to be placed, the desiredpercentage of the pathogen to be inactivated, the desired intensity fromthe UV light source, and the desired UV dose. According to any of theembodiments, the housing 111 has a height in the range of ¼ inch to 10inches, a width in the range of ¼ inch to 10 inches, an outer diameterin the range of ¼ inch to 10 inches, an inner diameter in the range of ⅛inch to 9¾ inches, a thickness in the range of ⅛ inch to 5 inches, and alength in the range of 1 inch to 50 feet.

According to any of the embodiments, at least a portion of the housing111 is transparent. As shown in FIG. 2, the base portion of theconical-shaped housing 111 can be open (i.e., not covered) or caninclude a transparent lens 113. The transparent lens 113 can be madefrom a variety of materials including, without limitation, glass, glassincluding a rare earth element, or plastic. The material for thetransparent lens 113 can also be designed such that amplification of theUV light emitted from the UV light source 112 occurs. By way of example,a glass including a rare earth element and a magnifying glass made fromglass or a plastic (e.g., poly(methyl methacrylate) “PMMA ”) having aconvex shape can cause amplification of the UV light emitted. Thehousing 111 can also be made entirely from a transparent material, forexample as shown in FIG. 3.

The UV light-emitting device 110 also includes an ultraviolet (UV) lightsource 112 located within the housing 111, wherein the UV light source112 emits ultraviolet light at a predetermined peak wavelength. The UVlight source 112 can be a UV lamp. According to certain embodiments, theUV lamp is a UV light-emitting diode (UV-LED). Advantages to using aUV-LED lamp over mercury-vapor lamps include, but are not limited to,the lamp is less fragile, there is no warm-up time, there is no risk ofmercury exposure, and the intensity of the UV light emission is constantfor the duration of UV light emission. Other types of UV lamps and lightsources can be used depending on the desired predetermined peakwavelength. For example, incandescent lamps, gas-discharge lamps, xenonarc lamps, deuterium arc lamps, mercury-xenon arc lamps, andmetal-halide arc lamps can be used. One of ordinary skill in the artwill be able to select the specific UV light source 112 based in part onthe pathogens to be targeted in the HVAC system 100 and the peakwavelength required to inactivate the pathogens. The portion of thehousing 111 that is transparent allows the emitted UV light to interactwith air flowing through the HVAC system 100 in the direction D1; thus,inactivating the pathogen(s).

According to any of the embodiments, more than one UV light source 112can be located within the housing 111. The more than one UV lightsources can be connected in series. FIGS. 1 and 3 show a plurality of UVlight sources contained within a transparent housing 111—commonlyreferred to as a “rope light.” If more than one UV light source islocated within the housing, the peak wavelength emitted from each UVlight source can be the same or different. The UV light-emitting device110 can include a housing 111 that houses a first UV light source 112 aand a second UV light source 112 b emitting different peak wavelengths,for example as shown in FIG. 3. By way of example, the first UV lightsource 112 a can emit a peak wavelength of 222 nm, and the second UVlight source 112 b can emit a peak wavelength of 270 nm. By way ofanother example, the first UV light source 112 a can emit a peakwavelength of 222 nm and the second UV light source 112 b can emit apeak wavelength of 254 nm. The UV light source 112 can also be a pulsedUV light source that emits a wide range of wavelengths, for example,from 200 to 320 nm. Although shown in FIG. 3 as the first and secondlight sources 112 a/112 b alternating, it is to be understood that a rowof multiple first light sources can be connected series and a row ofmultiple second light sources can be connected in series in a differentlocation of the same housing. By way of another example, a plurality offirst light sources can be connected in series and a plurality of secondlight sources can be connected at the end of the firstseries—preferably, in order to share a common power source. Arrangementswithin the same housing as alternating, series, connected series, etc.of a third, fourth, and so on light sources may also be designed.

The peak wavelength emitted can be selected based in part on thespecific pathogen that is targeted and that pathogen's sensitivity tothe peak wavelength. It is to be understood that the wavelength emittedcan be a range, for example, in the range of 260-268 nm. As used herein,the “peak wavelength” is defined as the single wavelength where theradiometric emission spectrum of the light source reaches its maximum.According to certain embodiments, the peak wavelength is in the UV-Crange of 100-280 nm and the pathogens that are targeted are SARS-CoV-2and influenza virus.

The HVAC system 100 can also include more than one housing 111. Anyadditional housings can be located within the same component of the HVACsystem 100 or located within a different component of the HVAC system100. By way of example and as shown in FIG. 1, a first housing 111 a canbe located within the return air duct 121 and/or the return plenum 122,a second housing 111 b can be located within the supply plenum 125 and asupply air duct 127, and a third housing 111 c can be located within thesupply plenum 125 and a different supply air duct 127. By way of anotherexample, a first housing 111 a can be located within the supply plenum125 and additional housings can be located within each of the supply airducts 127. Additional housings may be useful to increase the combined UVdose of the UV light exposure to the air flowing through the HVAC systemin the direction D1.

The total number and location of additional housings can be selected anddesigned based in part on the air flow rate through the HVAC system, theintensity of the UV light that is emitted from each UV light source, andthe dimensions of the transparent portion of the housing inter alia. Thepeak wavelength that is emitted from the UV light sources located withinthe first, second, third, and so on housings can be the same ordifferent. As used herein, the phrase “the same” regarding the peakwavelength means within (+/−) 5 nanometers of each other and are closeenough to one another to be considered to target the same pathogen. Asused herein, the phrase “different” regarding the peak wavelength meansmore than +/−5 nanometers of each other and are far enough apart fromeach other to be considered to target different pathogens. By way ofexample, the first housing 111 a can include one or more of a first UVlight source 112 a that emits a peak wavelength of 222 nm, and thesecond housing 111 b can include one or more of a second UV light source112 b that emits a peak wavelength of 270 nm. As discussed above, asingle housing (e.g., the first housing 111 a) can house both a first UVlight source 112 a and a second UV light source 112 b. There can also bemore than two different UV light sources each emitting different peakwavelengths, for example a third UV light source, a fourth UV lightsource, etc.

As shown in FIGS. 1 and 3, for housings including a plurality of UVlight sources that are connected in series—commonly referred to as a“rope light”—the housing 111 can be cylindrical or cubic in shape andmade from a transparent, flexible material. The transparent, flexiblematerial can be a heavy-duty plastic, such as polyvinyl chloride(“PVC”). In this manner, the housing 111 can curve to conform to theHVAC component without breaking. For example, air ducts generally curveand contain bends in order to connect return air ducts from a returnvent to the return plenum or to connect supply air ducts from the supplyplenum to supply vents. As can be seen in FIG. 1, a second housing 111 band a third housing 111 c are located within the supply plenum 125 andsupply air ducts 127.

The UV light-emitting device 110 can include a power source 114. Thepower source 114 can supply power to components of the device, such asthe UV light source 112. The power source 114 can be any source, such asa direct supply and/or batteries. The plurality of housings 111 a/111b/111 c can be connected in parallel to a common power source 114 oreach housing that houses the UV light source 112 can have its own powersource.

The intensity of the UV light source can vary or be predetermined. TheUV light-emitting device 110 can be configured to provide a desiredintensity. By way of example, in order to provide the desired intensity,the UV light-emitting device 110 can further include a wave amplifier(e.g., a mirror or plurality of mirrors or a magnifying glass), notshown. The wave amplifier can amplify the peak wavelength such that agreater number of pathogens are inactivated. The UV light-emittingdevice 110 can be designed such that a desired percentage of a targetedpathogen is inactivated. The desired percentage can be the percentagenecessary to sanitize the air flowing through the HVAC system 100 in thedirection D1. The desired percentage can also be 70%, 80%, or 90%. Theintensity of the UV light source 112 can be selected and designed suchthat the desired percentage of the targeted pathogen is inactivated.

The UV dose can also vary and be selected such that the desiredpercentage of the targeted pathogen is inactivated. According to any ofthe embodiments, the UV dose emitted by the one or more UV lightsource(s) 112 is the D90 for the specific pathogen to be inactivated.According to any of the embodiments, the UV dose emitted by the one ormore UV light source(s) 112 is at least 30 J/m², at least 40 J/m², or inthe range of 30 to 60 J/m². The UV dose can be increased by increasingthe intensity and/or the exposure time of the air flowing through theHVAC system 100 that is contacted by the UV light emitted from the UVlight-emitting device 110. The exposure time can be increased, withoutlimitation, by increasing the length of the transparent portion of thehousing 111, increasing the number of housings, increasing the number ofUV light sources 112, selecting the placement of numerous housingswithin different components of the HVAC system (e.g., the supply plenumand all supply air ducts), amplifying the peak wavelength emitted, andcombinations thereof. By way of example, a first housing 111 a can beplaced within the supply plenum 125 and can have a length in the rangeof 6 inches to 5 feet, a second housing 111 b can be placed within aprimary supply air duct 127 whereby all other supply air ducts branchoff from the primary supply air duct and can have a length selected tospan some of or the entire length of the primary supply air duct, and athird housing 111 c can be placed within the return plenum 122 and canhave a length ranging from 6 inches to 5 feet. The number of UV lightsources 112 that are housed within each housing 111 can also range from1 to 100, and the spacing of the UV light source 112 can be selected toinactivate the desired percentage of the targeted pathogen.

As discussed above, the UV light-emitting device 110 can be designed toinactivate a desired percentage of more than one type of pathogen. Byway of example, one or more of a first housing 111 a can contain one ormore of a first UV light source 112 a that emits a peak wavelength thattargets a first pathogen, and one or more of a second housing 111 b cancontain one or more of a second UV light source 112 b that emits a peakwavelength that targets a second pathogen. By way of another example,the same housing 111 can contain one or more of a first UV light source112 a and one or more of a second UV light source 112 b, wherein thefirst and second UV light sources emit different peak wavelengths thattarget a first and second pathogen, respectively, for example as shownin FIG. 3. Other combinations are also possible, and one of ordinaryskill in the art can design the UV light-emitting device 110 to target amultitude of different pathogens based on the disclosures herein.

The UV light-emitting device 110 can include an attachment component(not shown). The attachment component can allow the various components(e.g., the housing 111) of the UV light-emitting device 110 to beremovably secured to a component of an HVAC system 100. By way ofexample, for a rope-light-type housing, the UV light-emitting device 110can include clips or tape or VELCRO® for removably securing the ropelight housing to an inside perimeter of an air duct or a plenum. By wayof another example in a motor vehicle, the UV light-emitting device 110can include clips or tape or other attachment means for removablyattaching the housing to an air inlet and/or hoses that are connected tocabin vents. According to any of the embodiments, the housing 111 ispermanently or removably attached to the component of the HVAC system100 such that the UV light emitted from the UV light source 112 isdirected towards air flowing through the HVAC system 100. Accordingly,the bottom portion of the housing 111 at the location of the first andsecond UV light sources 112 a/112 b shown in FIG. 3 for example would belocated along an inner perimeter of the HVAC system such that the UVlight is directed into the inside of the HVAC component, for example, anair duct. In this manner, the UV light is directed to contact air as itmoves through the HVAC system 100 instead of directed to contact theHVAC component and not the air.

The UV light-emitting device 110 can include an activation switch (notshown). The activation switch can activate the UV light source 112 suchthat the UV light source 112 emits the peak wavelength. The activationswitch can be located on any portion of the UV light-emitting device110, any component of the HVAC system 100, or a different location, forexample, a thermostat or activation plate on a wall. The activationswitch can be manually activated by turning the activation switch to an“on” position directly on the activation switch or remotely, forexample, via a remote control. Activation of the UV light source 112 canalso be accomplished via a relay switch that triggers and activates theUV light source only when air is flowing through the HVAC system 100,for example, when the fan of the HVAC system is turned on. By way ofexample, the UV light source 112 can be activated via a low-voltagesignal from an HVAC control board when air is flowing through the HVACsystem. By way of another example, the UV light source 112 can beconstantly emitting UV light if the UV light source is wired directly tothe HVAC system's low-voltage transformer 126. In certain embodiments,the UV light source 112 does not continuously emit UV light.

Therefore, the present invention is well adapted to attain the ends andadvantages mentioned as well as those that are inherent therein. Theparticular embodiments disclosed above are illustrative only, as thepresent invention may be modified and practiced in different butequivalent manners apparent to those skilled in the art having thebenefit of the teachings herein. Furthermore, no limitations areintended to the details of construction or design herein shown, otherthan as described in the claims below. It is, therefore, evident thatthe particular illustrative embodiments disclosed above may be alteredor modified and all such variations are considered within the scope andspirit of the present invention.

As used herein, the words “comprise,” “have,” “include,” and allgrammatical variations thereof are each intended to have an open,non-limiting meaning that does not exclude additional elements or steps.While compositions, systems, and methods are described in terms of“comprising,” “containing,” or “including” various components or steps,the compositions, systems, and methods also can “consist essentially of”or “consist of” the various components and steps. It should also beunderstood that, as used herein, “first,” “second,” and “third,” areassigned arbitrarily and are merely intended to differentiate betweentwo or more housings, UV light sources, etc., as the case may be, anddoes not indicate any sequence. Furthermore, it is to be understood thatthe mere use of the word “first” does not require that there be any“second,” and the mere use of the word “second” does not require thatthere be any “third,” etc.

Whenever a numerical range with a lower limit and an upper limit isdisclosed, any number and any included range falling within the range isspecifically disclosed. In particular, every range of values (of theform, “from about a to about b,” or, equivalently, “from approximately ato b,” or, equivalently, “from approximately a-b”) disclosed herein isto be understood to set forth every number and range encompassed withinthe broader range of values. Also, the terms in the claims have theirplain, ordinary meaning unless otherwise explicitly and clearly definedby the patentee. Moreover, the indefinite articles “a” or “an,” as usedin the claims, are defined herein to mean one or more than one of theelement that it introduces. If there is any conflict in the usages of aword or term in this specification and one or more patent(s) or otherdocuments that may be incorporated herein by reference, the definitionsthat are consistent with this specification should be adopted.

What is claimed is:
 1. An ultraviolet light-emitting device for use in aheating, ventilation, and air conditioning system, the devicecomprising: a first housing located within a component of the heating,ventilation, and air conditioning system, wherein at least a portion ofthe first housing is transparent; a first ultraviolet light sourcelocated within the first housing and adjacent to the portion of thetransparent housing, wherein the first ultraviolet light source emitsultraviolet light at a pre-selected peak wavelength; and a power sourcefor supplying power to the first ultraviolet light source.
 2. Theultraviolet light-emitting device according to claim 1, wherein thehousing has a conical shape.
 3. The ultraviolet light-emitting deviceaccording to claim 2, wherein a portion of the housing is opaque.
 4. Theultraviolet light-emitting device according to claim 3, wherein a baseof the conical-shaped housing is open or is covered by a transparentlens.
 5. The ultraviolet light-emitting device according to claim 4,wherein the transparent lens has a convex shape, and wherein thetransparent lens amplifies the ultraviolet light emitted from the firstultraviolet light source.
 6. The ultraviolet light-emitting deviceaccording to claim 1, wherein the housing has a cylindrical shape, andwherein the housing is completely transparent.
 7. The ultravioletlight-emitting device according to claim 1, wherein the firstultraviolet light source is an ultraviolet lamp.
 8. The ultravioletlight-emitting device according to claim 7, wherein the ultraviolet lampis an ultraviolet light-emitting diode lamp.
 9. The ultravioletlight-emitting device according to claim 1, wherein the first housingfurther comprises a second ultraviolet light source.
 10. The ultravioletlight-emitting device according to claim 9, wherein the firstultraviolet light source and the second ultraviolet light source emit apeak wavelength that are the same.
 11. The ultraviolet light-emittingdevice according to claim 9, wherein the first ultraviolet light sourceand the second ultraviolet light source emit a peak wavelength that arethe different.
 12. The ultraviolet light-emitting device according toclaim 1, wherein the peak wavelength is in the UV-C range of 100-280nanometers.
 13. The ultraviolet light-emitting device according to claim1, further comprising: a second housing located within a component ofthe heating, ventilation, and air conditioning system, wherein at leasta portion of the second housing is transparent; a second ultravioletlight source located within the second housing and adjacent to theportion of the transparent housing, wherein the second ultraviolet lightsource emits ultraviolet light at a pre-selected peak wavelength; and apower source for supplying power to the second ultraviolet light source.14. The ultraviolet light-emitting device according to claim 13, whereinthe second housing is located within the same component of the heating,ventilation, and air conditioning system as the first housing.
 15. Theultraviolet light-emitting device according to claim 13, wherein thesecond housing is located within a different component of the heating,ventilation, and air conditioning system from the first housing.
 16. Theultraviolet light-emitting device according to claim 13, wherein thepeak wavelength that is emitted from the first ultraviolet light sourceis the same as the peak wavelength that is emitted from the secondultraviolet light source.
 17. The ultraviolet light-emitting deviceaccording to claim 13, wherein the peak wavelength that is emitted fromthe first ultraviolet light source is different from the peak wavelengththat is emitted from the second ultraviolet light source.
 18. Theultraviolet light-emitting device according to claim 1, wherein theultraviolet dose that is emitted from the ultraviolet light-emittingdevice is selected such that a desired percentage of a targeted pathogenis inactivated.
 19. The ultraviolet light-emitting device according toclaim 18, wherein the desired percentage is greater than or equal to70%.
 20. The ultraviolet light-emitting device according to claim 18,further comprising an amplifier that amplifies the intensity of theultraviolet light emitted from the first ultraviolet light source.